The present invention concerns a method of identifying a person, and an identification device implementing such an identification method. It finds an application in the field of biometric recognition and in particular in the field of identification by analysis of the irises of the eyes.
Identification by biometric recognition is used for protecting installations such as for example buildings or machines or for obtaining the granting of rights, such as for example the issue of an identity card, the payment of a pension, etc. This technology makes it possible to dispense with access codes or cards, which may be stolen or falsified. Use of this technology reinforces security since the probability that two persons have two identical biometrics is almost zero.
An eye comprises, from the center towards the periphery, the pupil, the iris and the sclerotic.
Identification by biometric recognition is more particularly based on analysis of the iris.
The document EP-A-0 661 037 discloses a method of identifying a person by his iris that comprises the steps of:                capturing an image of an eye to be identified,        determining an interior limit between the pupil and the iris from the said image,        determining an exterior limit between the iris and the sclerotic from the said image,        defining at least one analysis band between the internal limit and the external limit, the radial width of a band being defined as a fixed fraction of the radial width of the iris,        analysing each analysis band,        generating a present code associated with each analysis,        comparing the present code with a reference code,        measuring the resemblance between the present code and the reference code, and        making a decision concerning the identity of the person from the result of the measurement.        
The identification method is implemented through the establishment of a system of polar coordinates.
Such an identification method has the disadvantage of making it necessary to determine the limit between the iris and the sclerotic. However, this limit is very difficult to determine for various reasons, such as for example the fuzziness of the boundary area.
In addition, such an identification method requires very lengthy calculation times to enable good determination of the limit between the iris and the sclerotic and to determine the various analysis bands. These calculation times are incurred for each identification attempt whether or not the iris to be identified is included in the data base.
For example, in the document entitled “Recognising Persons by their Iris Patterns” written by John Daugman, it is stated that the identification method used is divided up according to the time scheme:
Location of the eye and iris: 408 milliseconds,
Adjustment of the boundary of the pupil: 76 milliseconds,
Detection and adjustment of the eyelids: 93 milliseconds,
Demodulation and creation of the code: 102 milliseconds,
Comparison of two codes: 10 microseconds.
This scheme shows clearly that the location of the eye and iris and the adjustment of the boundary of the pupil are lengthy steps that must be reduced in order to reduce the time necessary for identification.